Many clinical disorders are characterized as etiologically diverse, thereby complicating diagnosis and treatment. Diabetes mellitus, the most prevalent of the endocrine diseases, is one example. The disease, which is characterized by metabolic abnormalities and by long-term complications involving the eyes, kidneys, nerves and blood vessels, has been estimated to affect between 1-2% of the population.
The National Diabetes Data Group has defined two broad Categories: insulin-dependent diabetes and non-insulin-dependent diabetes. A therapeutic regimen including insulin therapy does not necessarily imply a disease classification of insulin-dependence. Rather, the term insulin-dependent is applied to that subcategory of diabetics at risk for ketoacidosis in the absence of insulin. Many of the patients who receive insulin therapy to control plasma glucose levels are not at risk for ketoacidosis if exogenous insulin is not administered.
A further classification which appears in the literature is the primary and secondary classification. The primary classification implies that no associated disease is present, while the secondary classification indicates some associated abnormality which causes or allows a diabetic syndrome to develop (e.g., pancreatic disease, hormonal abnormalities, drug or chemical induction, insulin receptor abnormalities, genetic disorders, etc.).
In light of the fact that a significant percentage of identical twins remain discordant for diabetes, an environmental factor (e.g., viral infection of beta cells) is believed to play a role in the development of many diabetic syndromes. It is possible, however, to identify genetic abnormalities as likely causes for diabetic syndromes. The ability to associate a specific etiology with a particular clinical disorder, such as a diabetic syndrome, is valuable to the clinician in formulating a therapeutic regimen.